Serotonin (5-HT) neurotransmission plays an important role in numerous physiological processes both in health and in psychiatric disorders. For example, 5-HT has been implicated in the regulation of feeding behavior. 5-HT is believed to work by inducing a feeling of fullness or satiety so eating stops earlier and fewer calories are consumed. It has been shown that a stimulatory action of 5-HT on the 5HT2C receptor plays an important role in the control of eating and in the anti-obesity effect of d-fenfluramine. As the 5-HT2C receptor is expressed in high density in the brain (notably in the limbic structures, extrapyramidal pathways, thalamus and hypothalamus i.e. PVN and DMH, and predominantly in the choroid plexus) and is expressed in low density or is absent in peripheral tissues, a selective 5-HT2C receptor agonist can be a more effective and safe anti-obesity agent. Also, 5-HT2C knockout mice are overweight with cognitive impairment and susceptibility to seizure. Thus, the 5HT2C receptor is recognized as a well-accepted receptor target for the treatment of obesity, psychiatric, and other disorders.
In view of the growing demand for compounds for the treatment of disorders related to the 5-HT2C receptor, new and more efficient routes to 3-benzazepines are needed. The processes and compounds described herein help meet these and other needs.